High Performance CeO2- and Ce0.8Sm0.2O2-Modified Pt/C Catalysts for the Cathode of a DMFC

Abstract

The Pt/C catalysts modified with CeO2 and Ce0.8Sm0.2O2 have been prepared with designated structures such as CeO2-Pt-C and Ce0.8Sm0.2O2-Pt-C for the cathode of a direct methanol fuel cell (DMFC). X-ray diffraction and cyclic voltammetry analyses indicate that in higher weight percent Ce0.8Sm0.2O2 modified Pt/C, some of the active sites of Pt are covered by the amorphous ceria and samaria particles. These oxide-modified Pt/C catalysts exhibit a methanol tolerant behavior, and this behavior increases with increasing weight percent of ceria and samaria. The CeO2- and Ce0.8Sm0.2O2-modified Pt/C, particularly the latter catalysts used in the cathode of a DMFC, dramatically improve the performance than does the Pt/C when air is supplied at the cathode. The higher performance can be attributed to the observed methanol tolerant behavior as well as the higher mass transfer of oxygen from air promoted by the oxygen buffering action induced by the presence of Ce0.8Sm0.2O2 in the structure of Pt/C catalysts. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3125803] All rights reserved.